A comparison of entrainment in turbulent line plumes adjacent to and distant from a vertical wall
A comparison of entrainment in turbulent line plumes adjacent to and distant from a vertical wall
复制标题
邻近和远离垂直壁的湍流线羽流夹带的比较
DOI：
10.1017/jfm.2019.790
复制
发表时间：
2019
影响因子：
3.7
通讯作者：
Parker D
中科院分区：
文献类型：
--
作者：
Parker D
我们给出了二维线状羽流在中心垂直平面上的速度场和浮力场的同时二维测量：远离垂直边界的自由羽流和靠近垂直壁的壁羽。数据在欧拉坐标系和羽流坐标系中提供，遵循羽流的瞬时湍流/非湍流界面(TNTI)。我们给出了两个坐标系中的测量结果，并比较了两种流动中的卷吸作用。我们发现，壁面羽流中的卷吸系数值大于自由羽流的一半。通过考虑基于平均动能的卷吸系数的分解来研究卷吸的减少，其中计算了湍流产生、浮力和粘性项的相对贡献。通过考虑TNTI的统计数据以及环境和被吞没流体的条件垂直输送，也研究了减少的夹带。我们发现，壁面剪应力是不可忽略的，自由羽流表现出明显的曲折。根据TNTI的伸展程度来量化卷吸过程的影响，结果表明，在自由羽流中TNTI的长度较大，并且在自由羽流中观察到被吞没的环境流体的相对垂直输运增加了15%。最后，给出了两种坐标系下的湍流速度和浮力脉动、雷诺应力和湍流浮力通量。
We present simultaneous two-dimensional measurements of the velocity and buoyancy fields on a central vertical plane in two-dimensional line plumes: a free plume distant from vertical boundaries and a wall plume, adjacent to a vertical wall. Data are presented in both an Eulerian and a plume coordinate system that follow the instantaneous turbulent/non-turbulent interface (TNTI) of the plume. We present measurements in both coordinate systems and compare the entrainment in the two flows. We find that the value of the entrainment coefficient in the wall plume is greater than half that of the free plume. The reduction in entrainment is investigated by considering a decomposition of the entrainment coefficient based on the mean kinetic energy where the relative contributions of turbulent production, buoyancy and viscous terms are calculated. The reduced entrainment is also investigated by considering the statistics of the TNTI and the conditional vertical transport of the ambient and engulfed fluid. We show that the wall shear stress is non-negligible and that the free plume exhibits significant meandering. The effect of the meandering on the entrainment process is quantified in terms of the stretching of the TNTI where it is shown that the length of the TNTI is greater in the free plume and, further, the relative vertical transport of the engulfed ambient fluid is observed to be 15 % greater in the free plume. Finally, the turbulent velocity and buoyancy fluctuations, Reynolds stresses and the turbulent buoyancy fluxes are presented in both coordinate systems.
登录
查看更多内容
垂直平面湍流羽流的测量
DOI：
--
发表时间：
1989
期刊：
影响因子：
--
作者：
B. Ramaprian;M. Chandrasekhara
通讯作者：
M. Chandrasekhara
DOI：
--
发表时间：
1993
期刊：
影响因子：
--
作者：
A. Ferrier;D. R. Funk;P. Roberts
通讯作者：
P. Roberts
DOI：
10.1016/j.physd.2011.07.010
发表时间：
2012
期刊：
Physica D: Nonlinear Phenomena
影响因子：
--
作者：
P. Odier;J. Chen;R. Ecke
通讯作者：
R. Ecke
同时测量平面湍流射流的湍流/非湍流界面附近的速度和压力
DOI：
--
发表时间：
2016
期刊：
影响因子：
--
作者：
O. Terashima;Y. Sakai;K. Nagata;Yasumasa Ito;Kazuhiro Onishi;Yuichi Shouji
通讯作者：
Yuichi Shouji
平面自守浮力湍流绝热壁羽流的速度统计
影响因子：
3.6
作者：
R. Sangras;Z. Dai;G. Faeth
通讯作者：
G. Faeth